using the backup in the parent bug, converted and restored into a 2.1 installation.
i'm seeing the lesson module show up this error on top.

Error: mdb->get_record() found more than one record!
line 1290 of /lib/dml/moodle_database.php: call to debugging()
line 1353 of /lib/dml/moodle_database.php: call to moodle_database->get_record_sql()
line 1332 of /lib/dml/moodle_database.php: call to moodle_database->get_field_sql()
line 1311 of /lib/dml/moodle_database.php: call to moodle_database->get_field_select()
line 164 of /mod/lesson/view.php: call to moodle_database->get_field()
Error: mdb->get_record() found more than one record!
line 1290 of /lib/dml/moodle_database.php: call to debugging()
line 1353 of /lib/dml/moodle_database.php: call to moodle_database->get_record_sql()
line 1332 of /lib/dml/moodle_database.php: call to moodle_database->get_field_sql()
line 1311 of /lib/dml/moodle_database.php: call to moodle_database->get_field_select()
line 251 of /mod/lesson/view.php: call to moodle_database->get_field()

for some reason there is some duplicity going on.